Such a motor-type power device is disclosed in Japanese Patent Application Laid-Open No. 2005-278319. In that motor-type power device, an electric motor housing chamber on a right side in the vehicle width direction and a transmission housing chamber on a left side in the vehicle width direction are defined by a partitioning wall, and the configuration is such that oil that is supplied to the electric motor housing chamber and the transmission housing chamber from an oil pump driven by an electric motor can flow back and forth between the two housing chambers via an oil communication passage that penetrates through a lower portion of the partitioning wall.
The above described conventional motor-type power device comprises a resolver that detects a rotational position of a rotor shaft of an electric motor, disposed between the partitioning wall and the left side surface of the electric motor.
In the above described conventional motor-type power device, oil that is stored at the bottom of the transmission housing chamber is scooped up by a final driven gear to lubricate a differential gear or a reduction gear, and one part of the oil that is scooped up is fed into the inside of a hollow rotor shaft of the electric motor to thereby lubricate the electric motor with oil that passes through the rotor from inside the rotor shaft to the outside in the diametrical direction.
However, when the quantity of oil that is held in the electric motor housing chamber and the transmission housing chamber is too large, there is the problem that a resistance to stirring of the oil by the differential gear or rotor of the electric motor increases and a loss in the driving force occurs. Conversely, if the quantity of oil is too small, when the oil in the transmission housing chamber moves to the electric motor housing chamber through the oil communication passage or the oil in the electric motor housing chamber moves to the transmission housing chamber through the oil communication passage due to a centrifugal force accompanying turning of the vehicle, there is the possibility that oil will be insufficient and a lubrication failure will occur.
In particular, heretofore when oil of a transmission housing chamber that has a relatively small volume capacity moves to an electric motor housing chamber that has a relatively large volume capacity, there has been the problem that the oil in the transmission housing chamber is insufficient and a lubrication failure occurs at a differential gear or the like, and furthermore there is excess oil in the electric motor housing chamber and the stirring resistance of the oil with respect to the rotor of the electric motor increases.
Moreover, in the above described conventional device, since a resolver is disposed between the left side surface of the electric motor and a partitioning wall that separates the electric motor housing chamber and the transmission housing chamber, there has been the problem that it is necessary to disassemble all of the motor-type power device in order to perform maintenance or replacement of the resolver, and that work requires much time and labor.
Consequently, it can be considered that the ease of maintenance of the device can be improved by disposing the resolver between a bearing that supports the right end of the rotor shaft, and a bearing that supports the right end of a center shaft that is coaxially disposed inside the rotor shaft, at the right side surface of the electric motor, i.e. the right end side of the electric motor housing chamber, to thereby enable access to the resolver without it being obstructed by the electric motor.
However, when this kind of configuration is adopted, it is necessary to supply oil to the bearing that supports the right end of the rotor shaft and the bearing that supports the right end of the center shaft for lubrication, and there is the problem that if a large quantity of the oil flows into the electric motor housing chamber the resistance to stirring of the oil by the rotor of the electric motor will increase.
Moreover, in the above described conventional motor-type power device, since lubrication of the differential gear, the reduction gear, and the electric motor are performed with oil that is scooped up by the final driven gear, not only is it difficult to uniformly distribute oil to parts to be lubricated that exist around various portions of the motor-type power device, but there is also the problem that the stirring resistance of the oil at the time of scooping up the oil with the final driven gear is extremely large and causes an energy loss. Further, since it is necessary to secure a storage chamber to store oil that is scooped up, there is the problem that this leads to an increase in the volume capacity and weight of the case.